JPH0265656A - Coreless linear motor - Google Patents

Abstract

PURPOSE:To generate smooth thrust by arranging coreless coils and conducting them to the magnet plate facing a field magnet having N and S poles alternately held by a magnetic substance and by moving it parallel to the field magnet. CONSTITUTION:A plurality of field magnets 2 in length L are arranged on a magnetic substance 1 forming a rail with the direction of poles alternately reverse. A magnetic plate 4 facing the field magnet 2 is provided as a mover. A plurality of coreless coils 3 are installed to the plate 4 at the pitch of 4/3 L. In the center of a coreless coil 3 a Hall element 6 is provided, with which the movement of the plate 4 is detected. Conduction switching of coils 3 is performed by a control device 7. On both sides of the plate 4 isosceles triangles of height L are formed, which are moved by bearings 5 along the rail 1. The thrust received by the plate 4 is thereby unified and smoothly moved, so that constant speed with high precision is obtained. It is suitable for a copying machine and an image scanner.

Description

[Detailed Description of the Invention] The invention is applicable to high-quality copying machines, image scanners, etc.
11 which requires a constant speed of 11 degrees! This invention relates to a coreless linear motor connected to a linear drive source.

Conventional technology In recent years, linear motors have been developed with high-speed response and high-precision positioning characteristics.1. Taking advantage of features such as the embedding mechanism, many products have been commercialized as big amplifier drive parts for IF recording hard disks, optical disks, etc.

U.S. registered patents 4 are often used for these purposes.
This is a coreless linear motor using a coreless coil disclosed in Japanese Patent Publication No. 151447, Japanese Patent Publication No. 1907, etc. The former will be briefly explained using FIG.

The magnetic pole array A14 is arranged alternately N and S in the longitudinal direction on the magnetic body A I 2, and the magnetic pole array B14 is arranged on the magnetic body B13 opposite to this and out of phase with the magnetic pole array A14, and this gap is used as a magnetic pole array. It has a coil that can be moved in the direction, and moves by switching the energization to the coil according to the magnetic pole.
In this configuration, the magnetic circuit does not change regardless of the movement of the coil, so cogging does not occur and a smooth thrust is obtained.However, on the other hand, a large attractive force is generated between the magnetic bodies A and B that make up the magnetic circuit. The structure 11 that supports these is required to have extremely high rigidity.

Another configuration is a coreless linear motor with a magnetic pole on one side, as disclosed in Japanese Patent Laid-Open No. 61-9161. This is shown in FIGS. 4(a) and (bL[C) and will be briefly explained. The magnetic circuit includes a field magnet 6, an armature coil 3, a traveling magnetic body 7, and a magnetic plate 2. In such a configuration, the magnetic attraction force is applied only to the traveling magnetic body 7, no rigidity is required for the base l, and assembly is easy.

Problems to be Solved by the Invention However, in the case of the configuration disclosed in US Pat. Although the rigidity required for the structure 11 is extremely large, the magnetic material A has an attractive force.

B is very difficult to assemble.

In addition, in the coreless linear motor disclosed in JP-A-61-9161, the magnetic attraction force acting on the movable part along the running direction changes depending on the positional relationship between the running magnetic body 7 and the n magnet 6. Therefore, cogging occurs due to magnetic pole pinch, and clean running cannot be expected. In view of these problems, the present invention does not require structural rigidity even if the moving distance is large, and is easy to assemble. Moreover, the present invention provides a coreless linear motor that does not cause cogging.

Means for Solving the Problems In order to solve the above problems, the coreless linear motor of the present invention includes: a field magnet having alternating lengths of N and S magnetic poles; a magnetic body that holds the field magnet in close contact with each other; A coreless coil facing the field magnet, a magnetic flat plate holding the core and the coil, a guide means supporting the magnetic flat plate so as to be movable parallel to the field magnet, and a coreless coil facing the field magnet. and control means for energizing the coreless coil. In particular, the end face of the magnetic flat plate in the moving direction has a shape in which the width of the surface facing the field magnet decreases in the moving direction, and preferably has an apex above the magnetization center of the field magnet and has a height L in the moving direction. It is configured to have an isosceles triangular shape.

Effects of the present invention With the above-described configuration, it is possible to increase the length of the magnetic body without increasing the mechanical rigidity, and it is easy to assemble and can be used in the document scanning mechanism of a copying machine. Furthermore, it is possible to average out fluctuations in the magnetic attraction force acting along the running direction between the magnetic body and the magnetic flat plate by the shape of the end face of the magnetic body.

EXAMPLE Hereinafter, a coreless linear motor according to an example of the present invention will be described with reference to the drawings.

Fig. 1 is a schematic diagram showing the configuration of a coreless linear motor according to an embodiment of the present invention, and Fig. 2 is a plan view of a field magnet, a magnetic flat plate, and a coreless coil. In Figures 1 and 2, 1 is a rail that also serves as a magnetic material, 2 is a field magnetite that is glued to the rail 1 and has N and S magnetic poles alternately;
3 is three coreless coils, 4 is a movable part frame that also serves as a magnetic flat plate to which the coreless coils are adhered and held, 5 is a hair ring for supporting the movable part frame so that it can move parallel to the rail, and 6 is each coil. 7 is a control device, 8 is a coil, and a harness connecting the Hall element and the control device. Here, the end face of the magnetic flat plate has an isosceles triangular shape with the base being the width of the field magnetite and the height being the length L of the field magnetite.

Now, each Hall element detects the magnetic flux density due to the field magnet at each coil position, and the control circuit uses this signal to switch the energization of each coil. When the coil is energized, thrust is generated and the movable frame moves on the rail.
Regarding the energization switching method, there are many known methods such as a three-phase half-wave method and a three-phase full-wave power method. 34 [When using a full-wave type driver, the distance between the two sides facing the rectangular coil in the moving direction is set, and the distance between the centers of each coil is 4L/3, so that the distance between the coil and the field magnet is The generated thrust can be made uniform regardless of the relative positional relationship.

On the other hand, the attractive force exerted on the magnetic flat plate by the field magnet changes depending on the relative positional relationship between the two.

In particular, when the lines of magnetic force passing through the end face of the magnetic flat plate in the moving direction make an acute angle with respect to the moving direction of the magnetic flat plate, this attractive force acts in the moving direction of the magnetic flat plate. When the end face shape of the magnetic flat plate is a straight line perpendicular to the direction of movement, the force applied to the magnetic flat plate in the direction of movement changes with the pitch of the magnetic poles of the magnetite field. Therefore, although the thrust generated by the coil is uniform, the thrust of the motor is uneven.

According to the end face shape of the magnetic flat plate of the present invention, the acting force in this moving direction can be about 115.

Effects of the Invention As described above, the present invention provides a field magnet having alternating long N and S magnetic poles, a magnetic body that closely holds the field magnet, a coreless coil facing the field magnet, and a coreless coil that faces the field magnet. It includes a magnetic flat plate that holds the coil, a guide means that supports the magnetic flat plate so as to be movable parallel to the field magnet, and a control means that energizes the coreless coil according to the magnetic pole of the field magnet. The end face in the moving direction of the field magnet 7 has a shape in which the width of the face facing the field magnet 7 decreases in the moving direction. It becomes possible to average the force in the moving direction applied to the magnetic flat plate that varies between the ff pole and the switch L, and a smooth thrust force can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the configuration of a coreless linear motor according to an embodiment of the present invention, Fig. 2 is a plan view of a magnetic flat plate and a coreless coil, and Figs. 3 and 4 show a conventional coreless linear motor. It is an explanatory diagram. l...Rail, 2...Field magnet, 3...Coreless coil, 4...Moving part frame, 5...Hair ring , 6...
・Hall element, 7... Control device, 8...
·Harness.

Claims (9)

[Claims] (1) A field magnet having alternating N and S magnetic poles of length L, a magnetic body that holds the field magnet in close contact, a coreless coil facing the field magnet, and a magnet that holds the coreless coil. a flat plate; a guide means for supporting the magnetic flat plate so as to be movable in parallel with respect to the field magnet; and a control means for detecting the magnetic flux density of the field magnet and energizing the coreless coil; A coreless linear motor characterized in that the end face of the magnetic flat plate in the moving direction has a shape such that the width of the face facing the field magnet decreases in the moving direction. (2) The coreless linear motor according to claim 1, wherein the end face of the magnetic flat plate in the moving direction has a triangular shape with a height L in the moving direction. (3) The coreless linear motor according to claim (2), wherein the shape of the end face in the moving direction of the magnetic flat plate is an isosceles triangular shape having an apex above the magnetization center of the field magnet. (4) The coreless linear motor according to claim (1), wherein the total length of the magnetic flat plate in the moving direction is an integral multiple of the length L. (5) The coreless linear motor according to claim (1), wherein the field magnet is longer than the magnetic flat plate in the moving direction. (6) The coreless linear motor according to claim (1), wherein the coreless coil has a rectangular shape, and the distance between the centers of the sides perpendicular to the direction of movement is L. (7) The coreless linear motor according to claim (1), wherein the coreless coil is adhesively supported on a magnetic flat plate. (8) The coreless linear motor according to claim (1), wherein the magnetic flat plate has a conductor pattern for feeding power to the coreless coil. (9) The coreless linear motor according to claim (1), wherein the control means includes a Hall element placed at the center of the coreless coil.